Fluid pressure system



Feb. .6, 1940. A. A. LowEKE 2,189,013

FLUID PRESSURE SYSTEM` Filed Dec. 1l, 1937 5 Sheets-Sheet'l L L Y v/0 l -`/z 441- ATTORNEY. l

Feb. 6, 1940. A. A. LowEKE FLUID PRESSURE SYSTEM 4 Filed Dec.

3 Sheets-Sheet 3 v INVENTOR.

@neo/v 6?; L awa/ns' ATTORNEY.

Patented Feb. 6, 1940 FLUXD PRESSURE SYSTEM Aaron A. Loweke, Detroit, Mich., assignor to Hydraulic Brake Company, Detroit, Mich., a corporation of California Application December 11, 1937, serial No. 179,310

4 Claims.

This invention relates to fluid pressure systems.

Broadly the invention comprehends a fluid pressure system including a duplex fluid pressure producing device having connected thereto a pair of fluid pressure'actuated motors arranged for the operation of a shiftable element.

An object of the invention is to provide a iiuid pressure system including a fluid pressure producing device having means compensating for overcharging of the systems.

Another object of the invention is to provide a fluid pressure producing device including means Other objects and features of the invention will appear from the subjoined description taken in connection with the accompanying drawings, in Which- Fig. 1A is a top plan view of a motor vehicle chassis illustrating the invention as applied;

Fig. 2 is a vertical sectional view of the fluid pressure producing device;

Fig. 3 is a cross-sectional view, substantially on line 3-3, Fig. 2; A Fig. 4 is a sectional view substantially on line 4-4, Fig. 2;

Fig. 5. is a fragmentary View partly in section illustrating the actuating mechanism of a transmission including the iiuid pressure actuated motors; andl Fig. 6 is a fragmentary View illustrating the connection of the motors to the actuating mechanism for the transmission and the connection of the actuating mechanism to the transmission;

Referring to the drawings for more specific details of the invention, I0 represents the frame of a motor vehicle chassis supported on springs, not shown, suspended from a. front axle, also not shown, and a rear axle I2 having mounted thereon, for rotation, wheels I4 of conventional type. The axle I2 has connected therein a differential I6, and associated with the differential is a transmission I8 including a shiftable gear 20.

A casing 22 suitably 'secured to the housing of the transmission has mounted therein for oscillation a shaft 24 extending through and beyond the casing. The shaft has secured thereon within the casing a. sleeve 26 supporting a fork 28 embracingthe shiftable gear 20, and an ann 30 provided with spaced recesses 32 arranged adjacent the free end of the arm for the reception of a spring-pressed plunger 34 mounted on the wall of the casing, and suitably -secured to the shaft outside of the casing is an operating lever 5 36. By applying force to the lever 36, the shaft 24 is moved through an angle, and this movement of the shaft is. transmitted through the fork 28 to the gear `20, resulting in shifting the transmission to either high or low speed posi- 10 tions, where it is retained by the spring-pressed plunger entering one of the recesses 32 in the arm 30. 4

A fluid pressure producing device indicated generally at 40, includes a uid reservoir 42 open 15 at its top and also at its bottom.. The reservoir has a radial flange 44 at its top, and a corresponding radial flange 46 at its bottom. A

casting 48 has a radial flange 50 secured as by bolts 52 to the ange 46 at the bottom of the 20 reservoir with a gasket 54 interposed so as to eectively seal the union of the reservoir and the casting. This casting 48 includes corresponding parallel cylinders 56 and 58, opening into the reservoir at their upper ends, and closed 25 at their lower ends by heads 60 and 62 provided with discharge ports y64 and 66 controlled as by two-way valves 68 and 10.

The casting also includes a .pair of corresponding oppositely disposed double diametral cyl- 3o inders 'I2 and 14, closed at the ends thereof havingthe smaller diameters as by heads 16 andfl8, and open at the ends having the larger diameter. The cylinder l2 is connected as by a passage 80 to the cylinder 56, and the cylinder is con- 35 nected as by a passage 82 to the cylinder 58.

Corresponding pistons 84 and 86 reciprocable in the cylinders l2 andy 14 each include a body 88, fitted in that portion of the cylinder having the smaller diameter, and a ange fitted in 4G that portion of the cylinder having the larger diameter. The iiange normally seats on the annular shoulder at the junction of the large and small chambers of the cylinder. The piston has on its head a sealing cup 92` for inhibiting the 4 seepage of fluid past the piston, and a spring 94 interposed between'the cup and the head of the piston serves to retain the cup against displacement. A recess in the back of the piston receives one end of a spring 96, and the other end of this 50 spring is seated in a recess in an adjustable screw 98 mounted for travel in a plug |00 threaded in the' open en d of the cylinder.

Corresponding pistons I02 and |04 are mounted .for reciprocation in'the cylinders 56 and 58. 55

Each of these pistons includes a shell |06, open at one of its ends and closed at its other` end. The closed end provides a head |08, and this head has an axial port ||0 providing a comy munication between the shell .and that portion of the cylinder forward of the piston. A sealing cup ||2 seated on the head |08 has an axial opening ||4 of somewhat .smaller diameter than the diameter of the port so that the perimeter deflning the opening slightly overhangs the port. A spring seat ||6 nestled in the cup receives one end of a spring ||8 interposed between the seat and the valve controlling the discharge port of the cylinder. This spring serves to retain the cup and valve against displacement, and also to return the piston to its normal or retracted position against a stop |20.

A plunger |22, reciprocable in the shell |06, has one of its ends reduced so as to provide an annular shoulder |24 normally abutting the stop |20. The other end of the plunger has a reduced portion providing an annular shoulder |26, and

interposed between this shoulder and the back of the head of the shell is a spring |28 normally urging, the plunger to its retracted position. The plunger has a. plurality of spaced longitudinal passages |30 providing communications between the reservoir and the port ||0 in the head |08, and an extension |32 adapted to enter and close the port and also to engage the overhanging'perimeter of the cup so as to effectively seal the pOl't.

A pin |34 on the extension 32 projects through the port ||0 in the shell and the opening in the sealing cup ||4. The pin has on its free enda head |36, of greater diameter than the port I0 in the head |08, and the pin and its head are slotted as at |38. The pin serves to retain the plunger within the shell during the retraction stroke of the piston, and the slots |38 provide for the passage of fluid through the port in the shell and the opening in the sealing cup as the piston moves to its retracted position.

A ring v|40 has a radial ange |42 secured to the iiange 44 at ,the top of the reservoir as by bolts |44, with a suitable gasket |46 interposed.

This rngihas a concentric flang'e- |48 provided with a circumferential groove |60, the object of which will hereinafter appear, and depending from the ring into the reservoir are correspond- .ing diametrically disposed arms |62. A shaft |54 mounted on the-free end of the arms has journaled thereon a walking beam |56 including diametrically disposed arms |58 and, |60 engaging the plungers |22 of the pistons |02 and |04, and a centrally disposed upwardly extended arm |62 having on its free end a tooth |64` A shaft |66 mounted in the arms |52 above and parallel to the shaft |64, and secured against displacement by a set screw |68, has mounted thereon an operating lever |10. ,This operatinglever has on its lower end a tooth |12 for cooperation with the tooth |64 on the sleeve, and sleeved on tire operating lever is a flexible boot |14 having a bead on its lower edge fitted in the groove in the ange |48.

The discharge ports 64 and 66 of the cylinders 56 and 58 are connected by :duid pressure delivery pipes or conduits |16 and |18 to iluid pressure actuated motors and |82 arranged in oppositely disposed relation to one another on a suitable bracket |84, bolted or otherwise secured to the casing 22, vand the pistons |86 of the respective motors are connected as by a thrust pin |88 to the shifting lever 36 of the transmission. l

In a normal operation, upon actuating the operating lever |10, the tooth |12 thereon engages the tooth |64 on the arm |62 of the walking beam |66 and transmits force thereto, resulting in rocking the walking beam. 'Ihis movement of the .walking beam imparts force through the arm |58 thereof to the plunger |22 of the piston |02, resulting in advancing the'plunger.

VDuring the initial movement ofthe plunger t |22, the extension |32 thereon enters and effectively closes the port ||0 in the head of the piston |02, and thereafter the plunger and piston move on the compression stroke of the piston as a single unit. As the piston advances on its compression stroke, the uid in the cylinder 48 Upon completion of this operation, the tooth 80 |12 of the operating lever |10 overrides the tooth |64 on the arm |62 of the walking beam, whereupon the piston |02 is released and is returned under the influence of the spring ||8 to its retracted position against the stop |20, and during the return of the pistonto its retracted position there is relative movement between the plunger 22 and the piston |02, due to the tension on the spring |28, resulting -in opening'the port ||'0 in the head |08 of the piston and thereby establishing communication between the reservoir and that portion of the cylinder 48 forward of the piston, and as the piston and its associated plunger return to their retracted positions, the walking beam |56 is returned to its normal position.

When it is desired to shift the transmission from the low speed position to the high speed pomovement of the plunger, the extension |32' thereon enters and closes the port I 0 in the head of the piston |04, and thereafter the plunger and piston move on the compression strokeas 'a single unit.

As the piston advances on4 its compression stroke, the uid in the cylinder 68 forward of the piston is displaced therefrom, past the two-way valve 10, through the Adischarge port 66 and uid pressure delivery pipe |18, into the luid pressure actuated motor |82, causing energization of the motor. This energization Aof the motor results in shifting ythe lever 36, and this movement of the leverf36 rocks the shaft 24 and shifts the fork 28 and the gear 20 embraced thereby, resulting in shifting the transmission to the high speed position.

In shifting the transmission, it is highly desirable that the fluid pressure producing device and the fluid pressure motors connected thereto be brought into phase or synchronized, in order that the maximum displacement of the fluid pressure producing device may be substantiallyv equal to the maximum displacement of the fluid pressure actuated motors so that movement of the latter may be positively arrested at the end of the stroke. In the past this has been found difllcult because of an excess of iiuid in the system due to expansion and other causes, such as rocking of the operating lever |10, resulting in pumping fluid into the system. Under these conditions the column of iluid under pressure may be in excess of that necessary to eiectively shift the transmission, and, accordingly, the trapping action between the operating lever and walking beam is rendered impossible because of the locking action between the tooth |12 on the operating lever and the tooth 164 on the walking beam. To avoid this condition, the cylinders 56 and 68 have connected thereto auxiliary cylinders 12 and 1l having therein spring-pressed pistons 84 and 86; yieldable upon attaining a predetermined pressurein the cylinders G and 5B, the pressure in the cylinders being determined by the load onthe.

fore, to be limited only bythe yscope of the appended claims.

. Having thus described the various features of vthe invention, what I claim as new and desire to secure by Letters Patent is:

1. A iiuid pressure producing device comprising a reservoir, a pair of cylinders supplied therefrom,

pistons reciprocable in the cylinders, a support on the top of the reservoir, arms depending from the support into the reservoir, a walking beam supported by the arms for actuating the pistons,

and an operating lever mounted between the arms cooperating with the walking beam. l

2. A iiuid pressure producing device comprising a reservoir, a pair oi' cylinders depending from and communicating therewith, pistons reciprocable in the cylinders, a support on top of the reservoir, arms depending from the support into the reservoir, a walking beam supported by the arms for actuating the pistons, an upwardly extending arm on the walking beam, an operating lever mounted between the arms, and an extension on'the operating lever cooperating with the upwardly extended arm on the walking beam.

3. A iiuid pressure producing device comprising the operating lever cooperating with the arm on the walking beam, and a exible boot sleeved on the operatinglever embracing the support on the top oi' the reservoir.

4. A fluid pressure system comprising a reservoir, a pair of cylinders depending therefrom and communicating therewith, fluid pressure actuated motors connected to the cylinders', a shiftable element connected between the motors, a

kpiston reciprocable in each of the cylinders, an

auxiliary cylinder connected to each of the cylinders, a iluid pressure actuated piston in each of the auxiliary cylinders, springs resisting movement of the pressure actuated pistons, means for regulating the tension on the springs, a ring on the top of the reservoir, arms depending from the ring into the reservoir, ai walking beam supported between the arms for actuating the pistons, an operating lever mounted between the arms cooperating with the walking beam, and a ilexible boot sleeved on the operating lever embracing the ring on the top of the reservoir.

AARON A. LOWEKE. 

